RICKETTSIA-TSUTSUGAMUSHI IN CHIGGERS (ACARI, TROMBICULIDAE) ASSOCIATED WITH RODENTS IN CENTRAL THAILAND

Chiggers were collected from rodents trapped at two military bases loc ated 10 km apart in central Thailand. One site was swampy and nearly t reeless and the other site was well-drained and partially wooded. Alth ough 13 species of chiggers were collected, only three species were fo und to be positive for Rickettsia tsutsugamushi (Hayashi) Ogata using a direct fluorescent antibody test: Blankaartia acuscutellaris Walch ( 7.3% infected), Leptotrombidium deliense Walch (3.1% infected), and an undescribed species of Ascoschoengastia near A. indica Hirst (1.2% in fected). This was the first record of R. tsutsugamushi in B. acuscutel laris. The Ascoschoengastia species occurred with equal frequency at t he two study sites, L. deliense occurred more frequently at the well-d rained site, and B. acuscutellaris occurred more frequently at the swa mpy site. Results suggest that there are important foci of scrub typhu s in central Thailand and that B. acuscutellaris may be a vector in th is area.